1. Technical Field
The present invention relates to a printing apparatus such as an ink jet type printer and a printing control program that is executed in the apparatus.
2. Related Art
In the related art, as a type of printing apparatus, there has been known an ink jet type printer in which an ink as an example of a liquid is ejected to a medium transported in a predetermined direction from a print head moving in a direction orthogonal to a transport direction of the medium such that printing is performed. In such a printer, since the ink discharged from the print head has inertia in a moving direction of the print head, a landing position of the ink on a medium is subjected to a slight positional shift in the moving direction of the print head. In addition, when a space between a surface of the medium and the print head is changed, such a positional shift is changed depending on the degree of the change. Therefore, there is proposed a printing apparatus which controls discharge timing of discharging an ink on a medium from a moving print head, so as to suppress the positional shift in such a case, depending on a difference in the space between the surface of the medium and the print head (for example, see JP-A-2007-216480).
Incidentally, a positional shift of the landing position of the ink, which occurs when the print head discharges an ink while moving, is found in a transport direction of the medium, which intersects with the moving direction of the print head. For example, since a movement of the print head results in pushing the air in the moving direction so as to stir up a wind, the wind influences the landing position of the ink discharged from the print head so as to be subjected to the positional shift in a direction parallel to the transport direction of the medium. This type of positional shift occurs as a relative positional shift between an ink dot formed of ink, which lands by being discharged during a previous movement of the print head, and an ink dot formed of ink, which lands by being discharged during a current movement of the print head. In order for print quality not to be degraded, it is desirable to also suppress the relative positional shift between the dots, due to such a positional shift in the transport direction.
However, in this respect, JP-A-2007-216480 discloses technology of suppressing the positional shift occurring in the moving direction of the print head, through control of the discharge timing, but does not disclose any technology of suppressing the positional shift of the landing position of the ink in the transport direction of the medium. In addition, although the positional shift of the landing position of the ink in the transport direction is allowed, technology, in which degradation of print quality due to the positional shift is suppressed, has not been disclosed.